<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>EL执行运算</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
	算数运算：
	${90+90 }
	<br/>
	关系运算：
	${(6+4)!=(5+5)}
	<br/>
	逻辑运算：
	${!((5+5)!=10)}
	<br/>
	检查空值：
	<%
		String key1="";//true
		int[] key2=new int[5];//false
		String key3=" ";//false
		String key4=null;//true
		int[] key5=new int[0];//false
		request.setAttribute("key1", key1);
		request.setAttribute("key2", key2);
		request.setAttribute("key3", key3);
		request.setAttribute("key4", key4);
		request.setAttribute("key5", key5);
		
	
	 %>
	 
	 ${empty key1 }
	 ${empty key2 }	
	 ${empty key3 }
	 ${empty key4 }
	 ${empty key5 }
	 ${empty key6 }	
  </body>
</html>
